bad_error3.lean:1:33: error: type expected at
  p 0
bad_error3.lean:3:0: error: tactic failed, there are unsolved goals
state:
p : ℕ → ℕ → Prop
⊢ sorry
bad_error3.lean:5:32: error: type expected at
  p 0
bad_error3.lean:7:0: error: tactic failed, there are unsolved goals
state:
p : ℕ → ℕ → Prop
⊢ sorry
bad_error3.lean:5:4: warning: declaration 'ex' uses sorry